OBJETIVES: To evaluate underreporting of maternal mortality in Los Altos de Chiapas and to compare the results of this study against the RAMOS modified program conducted by the Ministry of Health. MATERIAL AND METHODS: A survey of all deaths of reproductive-aged women was carried out, followed by verbal autopsy interviews. RESULTS: A total of 226 deaths of reproductive-aged women were identified and 190 verbal autopsies were carried out. Verbal autopsies showed an underreporting of 19 maternal deaths. The method used by the Ministry of Health would have led to the detection of only eight out of these 19 deaths. CONCLUSIONS: Results of this study emphasize the urgency to improve the quality of cause of death certification in order to reduce maternal mortality underreporting. They also suggest the need to prevent government programs that allocate financial resources from creating incentives for concealing maternal deaths.